JP3039249B2 - Rolls for continuous casting of thin sheets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roll used in an apparatus for producing a thin plate of various steels such as carbon steel or an alloy such as stainless steel directly from a molten metal by a continuous casting method.

[0002]

2. Description of the Related Art FIG. 4 is a view showing a method of directly manufacturing a thin plate from a molten metal (hereinafter simply referred to as a molten metal) by continuous casting, where R is a roll, M is a molten metal, N is a casting nozzle, and D is a side dam. , S are thin cast pieces. FIG. 3A shows a method called a single roll method, in which a molten metal M is supplied to a continuously rotating roll R from a casting nozzle N provided on the side of the roll to cast a thin slab S. It is. Figure (b) and
(c) is a method called a twin roll method, in which a molten metal M is supplied between two rolls R, (b) a molten metal is supplied from above the rolls, and (c) is a molten metal from the side of the rolls. Supply,
It is to be cast.

[0003] Rolls used in these continuous casting methods often have a structure in which a sleeve made of copper or a copper alloy is fitted to a shaft core and a coolant is passed between the shaft core and the sleeve in order to increase the amount of heat removal. However, when this was used for casting of a thin slab, there occurred a phenomenon that the cooling ability was too large and the flatness of the thin plate was poor or cracks occurred.

In order to solve this problem, it has been attempted to use carbon steel, stainless steel, or the like as a sleeve material, which has a lower thermal conductivity than a copper alloy and has a moderate cooling of the slab, but the cooling capacity is too small. As a result, the temperature of the roll increased, and the thermal crown (phenomenon in which the diameter at the center of the roll increased due to thermal expansion) increased.

When the thermal crown is increased by the twin roll method,
A concave crown in which the cross-section perpendicular to the casting direction of the slab is thinner at the center in the width direction occurs, or the center in the thickness direction of the end is unsolidified and pulled out, resulting in a two-piece crack . Since these defects are difficult to correct in the next step, they deteriorate the quality of the product.

In the case of the single roll method or the twin roll method in which the molten metal is supplied from the side of the roll, the casting nozzle for holding the molten metal is in contact with the roll body length. A gap is created between them and the molten metal leaks out of the gap, making casting impossible.

Various methods have been proposed to reduce the thermal crown.

FIG. 3 is a view showing the structure of a conventional two-layer sleeve, wherein 1 is an outer sleeve, 2 is an inner sleeve, 3 is a roll axis, 4 is a core, and 5 is a flange provided on the axis. , 6 is a cooling water passage, D is a side dam, and S is a slab.

For example, two layers (or multiple layers) as described above
In the sleeve structure, a roll in which the inner sleeve 2 is made of a material having a coefficient of thermal expansion larger than that of the outer sleeve 3 (see Japanese Patent Application Laid-Open No. 3-133550), or a multi-layered sleeve, wherein the outer sleeve and the inner A roll has been proposed in which a step portion is provided between sleeves so that a predetermined portion of the outer sleeve is made thinner (see JP-A-64-44252). In addition, a roll with a negative (concave) roll crown that keeps the sleeve flat by applying internal pressure to the center to deform the sleeve outward
62-27905 and JP-A-60-33857).

[0010]

The roll disclosed in Japanese Unexamined Patent Publication No. 3-133550 is effective when the temperature of the inner sleeve and the outer sleeve is about the same, but is actually in contact with the high-temperature molten metal. The temperature of the outer sleeve becomes higher, and the thermal expansion becomes larger in the outer sleeve than in the inner sleeve. In particular, when carbon steel, stainless steel, or the like having a low thermal conductivity that makes cooling moderate is used for the outer layer, the temperature of the outer layer increases, and the effect of reducing the thermal crown is not so much recognized.

The roll disclosed in Japanese Patent Application Laid-Open No. 64-44252 has a low strength (rigidity) and is easy to bend because the thickness of the sleeve at the center of the roll width where the bending moment is large is reduced. For this reason, the thermal crown is reduced to about half of the conventional one, but the effect is small.

JP-B-62-27905 and JP-A-60-33
The roll disclosed in Japanese Patent No. 857 can correct a small thermal crown, but when carbon steel or stainless steel, etc., which cool the slab moderately, are used for the outer layer, the thermal crown becomes large. Requires a large internal pressure, which complicates the apparatus.

An object of the present invention is to provide a thin cast slab continuous casting roll capable of greatly reducing the thermal crown even when the outer sleeve is made of carbon steel, stainless steel, or the like, which cools the slab moderately. To offer.

[0014]

Means for Solving the Problems The present inventors have confirmed that the cause of the generation of the thermal crown is the restriction of the shaft core flange portion and the temperature difference in the width and thickness directions of the sleeve. completed.

The gist of the roll according to the present invention is as shown in FIG. 1, which is a description of a double-sleeve casting roll used in an apparatus for continuously manufacturing thin sheets directly from molten metal. The inner sleeve 2 is longer than the outer sleeve 1 and the portion 21 contacting the outer sleeve is thicker than the end 22 in the continuous casting. roll. "It is in.

The inner sleeve is preferably made of a material having a higher thermal conductivity than the outer sleeve.

[0017]

[Function] When the casting nozzle is installed on the roll body as in the single roll method, the body length of the casting roll is longer or equal to the width of the slab. When it is brought into close contact with the roll side surface, it becomes equal to the width of the slab.

In the roll structure shown in FIG. 3, the outer sleeve becomes hot and thermally expands regardless of the slab width and the body length of the outer sleeve. Since it is fitted to the flange of the shaft core, expansion in the axial direction is restricted, and thermal expansion does not occur.
Further, at both ends of the outer layer sleeve, the axial deformation of the flange of the roll shaft core is restricted via the inner layer sleeve. As a result, the diameter of the central portion of the outer layer sleeve increases, and a thermal crown occurs.

This thermal crown becomes remarkable when carbon steel or stainless steel having a low thermal conductivity is used for the outer layer sleeve. In order to prevent this, the deformation of the outer sleeve in the axial direction is released from the restraint of the flange, and the trunk length of the inner sleeve is made longer than that of the outer sleeve as shown in FIG. Further, in order to suppress thermal deformation of the outer sleeve, a portion 21 where the inner sleeve contacts the outer sleeve is made thick. Also, the inner sleeve end
22 thins the part 23 not restrained by the flange,
We tried to ease the constraint of the flange.

It is desirable to select a material having a higher thermal conductivity than the outer sleeve so that the inner sleeve itself does not become hot and is not thermally deformed.

As described above, in the roll having the double sleeve structure, the inner sleeve is longer than the outer sleeve and the thickness of the portion where the outer sleeve is fitted is made thicker, so that the thermal crown can be formed more than the conventional roll. It was confirmed that it could be suppressed.

Further, the configuration and operation of the roll of the present invention will be specifically described with reference to the drawings.

FIGS. 1A and 1B are views showing an example of the structure of the roll of the present invention. FIG. 1A is a cross-sectional view in a longitudinal direction, and FIG. 1B is a cross-sectional view in a direction perpendicular to an axis. 1 is an outer sleeve, 2 is an inner sleeve, 3 is a roll axis, 4 is a core, 5 is a flange of the roll axis, 6 is a cooling water passage, D is a side dam, and S is a cast piece. The outer sleeve 1 is made of a material (alloy steel or stainless steel) having a thermal conductivity of 8 to 60 W / (m · K) and excellent heat resistance in order to slowly cool the slab S.
Has a thermal conductivity of 300 to 400 W /
A material (copper or copper alloy) having an excellent cooling capacity of (m · K) is used.

The thickness of the inner layer sleeve is thicker than the outer layer,
In addition, the thickness of the portion 21 contacting the outer layer is made larger than that of the end portion 22 contacting the flange 5, so that heat transfer and rigidity in the radial direction are increased. This provides a structure that can prevent thermal deformation.
The length of the inner sleeve is made longer than that of the outer sleeve, and the portion 23 from the end of the outer layer to the inner surface of the flange is made thinner to absorb the restraint of the flange and the thermal crown. This deforms the thinned portion 23 of the inner sleeve, but makes casting impossible,
It was confirmed that there was no adverse effect on the cross-sectional shape of the slab.

The roll of the present invention having such a structure can greatly reduce the thermal crown without complicating the structure. Particularly effective when alloy steel or stainless steel, which has low thermal conductivity and can cool the slab slowly, is used for the outer layer sleeve. A thin sheet product with good properties is obtained,
With the single roll method, stable casting can be performed without an accident that the molten metal leaks.

FIGS. 2A and 2B are views showing another embodiment of the roll of the present invention, wherein FIG. 2A is a view showing a state of casting by applying a single roll method, N is a casting nozzle, and FIG. () Is a diagram showing a mode in which the thickness of the portion in contact with the outer layer of the inner layer sleeve is increased, in which a thick portion is provided on the inner surface side of the inner layer sleeve.

[0027]

EXAMPLES Hereinafter, the effects of the present invention will be described in more detail with reference to examples.

The casting roll of the present invention has the shape shown in FIG.
It was manufactured as follows.

The outer sleeve has an outer diameter of 600 mm and a length of 240 mm.
, Thickness 6mm, Inconel 718 (trade name, 52% Ni, 1
9% Cr, 5% Nb, 3% Mo, 0.9% Ti, 0.5% Al, balance F
e, thermal conductivity 11.2 W / (m · K) (room temperature)). The inner sleeve has an inner diameter of 468mm, a length of 440mm (the thickness of the thick part at the center of the width is 240mm), the thickness of the thick part at the center of the width is 60mm, and the thickness of the thin part at the end is 20mm. 1.2%
Cr, 0.13% Zr, balance Cu, thermal conductivity 352 W / (m · K) (
Room temperature)). The roll core and core are made of carbon steel (JIS
SS41) was used.

In the comparative example, a casting roll having the shape shown in FIG. 3 was used. The outer sleeve has an outer diameter of 600 mm, a length of 240 mm, and a wall thickness of 6 mm. The inner sleeve has an inner diameter of 468 mm and a length of 240 m.
m, the thickness was 6 mm, and the other conditions were the same as those of the above-mentioned invention.

The casting test was carried out using austenitic stainless steel (SUS304) molten metal (about 2 tons) at 1520 ° C and a width of 240 mm and a thickness of 240 mm.
A 2.3 mm slab was cast at a casting speed of 30 m / min. The flow velocity of the cooling water in the casting roll was 5.2 m / s (flow rate 0.04 m ³ / s).

(Example 1) The casting rolls of the present invention and the comparative example were applied to the twin-roll method shown in FIG. 4 (b), and each was cast for 10 charges. It was measured.

When the casting roll of the example of the present invention is used, FIG.
On the other hand, the average was 0.18 mm as shown in FIG. 2, while the average was 0.59 mm when the casting roll of the comparative example was used.

FIG. 6 is a diagram showing the amount of deformation (calculation result) at the closest position of the roll during casting. The amount of deformation generated at the closest position of the roll during casting under the above-described casting conditions is represented by a finite element. It is the result of analysis by the method. From the figure, it was confirmed that the deformation (crown amount) of the casting roll of the present invention was 0.11 mm, whereas the deformation amount of the conventional casting roll was 0.32 mm, which was almost similar to the test result. .

Example 2 The casting roll used in Example 1 was applied to the single roll method shown in FIG. 4 (a), a casting test was performed, and a casting amount until the casting was interrupted by a thermal crown was measured.

With the casting roll of the present invention, 18 charges were tested, and as shown in FIG. 7, 15 charges could be completely cast. The three charges in which the casting was interrupted were interrupted due to poor slab winding or a decrease in the temperature of the molten metal, and were not due to deformation of the roll.

On the other hand, 9 charges were tested with the conventional casting roll, and 2 charges were successfully cast as shown in the figure. However, at 7 charges, molten metal leaked from between the casting roll and the casting nozzle, and the casting was stopped. Interrupted. This is due to the thermal deformation of the roll.

[0038]

According to the casting roll of the present invention, the roll deformation during casting can be reduced, the crown of the slab is reduced (the center of the width of the strip is depressed), and the distance between the roll and the casting nozzle is reduced. Of molten metal from the metal can be reduced. Thereby, a thin plate product having a good plate shape can be stably manufactured.

[Brief description of the drawings]

FIG. 1 is a view showing a cross section of a casting roll of the present invention;
(a) is a sectional view parallel to the axis, and (b) is a sectional view perpendicular to the axis.

FIG. 2 is a view showing a cross section of another embodiment of the casting roll of the present invention, wherein (a) is a view showing an embodiment when used in a single roll method, and (b) is a view showing a thick portion of an inner sleeve. It is a figure showing the mode in the case of being provided inside the sleeve.

FIG. 3 is a diagram showing a cross section of a conventional casting roll.

4A and 4B are diagrams illustrating an embodiment of manufacturing a thin cast piece by a roll cooling method, wherein FIG. 4A is a diagram illustrating a single roll method, and FIGS. 4B and 4C are diagrams illustrating a twin roll method.

FIG. 5 is a diagram showing a crown amount of a thin cast piece by a twin roll method.

FIG. 6 is a diagram showing a roll deformation amount (calculation result) at a roll kiss point in the twin roll method.

FIG. 7 is a view showing a casting amount by a single roll method.

[Explanation of symbols]

1. Outer sleeve 2. Inner layer sleeve
3. Roll axis 4. Core 5. Shaft core flange
6. Cooling water passage D. Side dam N. Casting nozzle
S. Cast slab R. Casting roll M. Molten metal 21. Thick part of inner sleeve 22. End of inner sleeve 23. Thin part of inner sleeve

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP 5-253649 (JP, A) JP 5-154616 (JP, A) JP 2-142646 (JP, A) JP 3- Hei 6 133550 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B22D 11/06 330 B22D 11/04 311 B22D 11/059 120

Claims (2)

(57) [Claims] In a casting roll having a double sleeve structure used in an apparatus for continuously manufacturing thin sheets directly from molten metal, an inner sleeve covered with an outer sleeve is supported by a flange of a roll axis. The inner layer sleeve is longer than the outer layer sleeve, and a portion in contact with the outer layer sleeve has a greater thickness than an end portion. 2. The roll according to claim 1, wherein the inner sleeve is made of a material having a higher thermal conductivity than the outer sleeve.